1. Field of the Invention
The present invention relates to a simple method for recycling an optical disk to utilize a used optical disk effectively. The present invention also relates to a resin composition for forming a film, the resin composition containing the used optical disk as a raw material, and to a resin molded article.
2. Description of the Related Art
Optical disks such as a digital versatile disk (DVD), a compact disk (CD), a mini disk (MD), and a magneto optical disk (MO) are media widely used for reproducing or recording images, music, and various data. The importance of the optical disks has been increasing.
Used optical disks are disposed of as a large amount of waste as well as known tape media such as video tapes, e.g., VHS tapes and 8 mm-VTR tapes, and music tapes. The recycling of the optical disks, which are mainly composed of, for example, polycarbonate of the substrate material, has been desirable.
However, it is very difficult to reuse the used optical disks as new optical disks because these used optical disks include various films such as a reflective film, a recording film, an adhesive layer, a protective layer, and a printing ink layer, and also contain various additives. Contamination prevents the highly reliable optical properties.
For example, Japanese Unexamined Patent Application Publication Nos. 2001-287225, 11-57683, and 8-164524 disclose various technologies for reusing the substrate material, i.e., polycarbonate resin. According to these patent documents, the optical disk is treated with chemicals to separate and remove the above films on the disk and various additives.
Unfortunately, according the known arts described in the patent documents, the use of a large amount of chemicals generates a large amount of waste liquid. Consequently, these methods result in the high cost of the chemicals and generate more waste, i.e., the waste liquid and the waste water.
In the above circumstance, a social strong desire for efficient recycling of the used optical disk, a large amount of which will be exhausted in the future, has been increasing.